(1) Field of the Invention
The present invention relates to a sheet processing apparatus which selectively feeds one type of paper from multiple types of paper stored in a paper feeding portion to a processing portion where a predetermined process is implemented.
(2) Description of the Prior Art
In a sheet processing apparatus such as an image forming apparatus which feeds a sheet of paper from a paper feeding portion to a processing portion and performs a predetermined process for the fed paper, it is necessary to feed the paper of a size which corresponds to the process therefor. For example, in a copier for duplicating the image of an original onto a sheet of paper, it is necessary to feed the paper, which corresponds to the image size of the original and the copy magnification, to the processing portion. Various types of paper, different in material and thickness are fed in correspondence with the use of the sheets after processing. For example, when a cover page is duplicated in a copier, a different type of sheet, dissimilar in material and thickness from those used for duplication of the content images may be used.
In this way, among sheet processing apparatus to which different types of sheets may be fed from the paper feeding portion to the processor, there are models in which plural types of paper are accommodated beforehand in the paper feeding portion in order to allow for easy change of the paper to be fed, and one type of paper to be fed to the processing portion can be selected from plural types of paper accommodated in the paper feeding portion by operating the control means such as paper selection keys etc., in accordance with the processing conditions. In such a sheet processing apparatus, every time the control means is operated, the type of paper to be fed to the processing portion is switched and selected from the plural types of paper accommodated in the paper feeding portion, in the predetermined sequential order.
However, in a case of a sheet processing apparatus which can accommodate many types of paper in the paper feeding portion, the operator may have to operate the control means repeatedly many times before the operator's desired selection of paper as the type of paper to be fed to the processing portion, needing time-consuming complicated procedures for selecting the type of paper to be fed to the processing portion, resulting in degradation of operating efficiency of the sheet processing apparatus.
Japanese Patent Publication Sho 62 No. 40257 discloses a configuration in which when new paper is loaded, the type of paper newly loaded will be selected and fed to the processing portion regardless of the operated state of the control means. Thus, this disclosure demonstrated that, when the operator has loaded the desired type of paper to be used into the paper feeding portion, the newly loaded paper will be automatically selected and fed to the processing portion without any operation via the control means, thus making it possible to simplify the selecting task of the type of paper to be fed to the processing portion. This disclosure also mentioned that it is possible to prevent waste of paper due to erroneous paper feed when the operator forgot to operate the control means after the paper has been loaded in the paper feeding portion.
However, in the configuration disclosed in Japanese Patent Publication Sho 62 No. 40257, when new paper has been loaded, the operator cannot select the paper to be fed to the processing portion through the operation of the control means. That is, it becomes impossible to reflect the operator's intention for the choice of the paper to be fed to the processing portion. Therefore, when a type of paper which is not the one to be fed to the processing portion is newly loaded to the paper feeding portion, for example, as in the case where an operator notices that, among the plural types of paper, a type of paper which should be stored in the paper feeding portion but is not the desired one to be fed to the processing portion is used up and supplies the paper, or as in the case where another operator other than the operator who is going to select the paper type supplies the paper to the paper feeding portion, paper which is not desired by the latter operator will be fed to the processing portion, thus giving rise to a failure to feed correct paper.